1. Technical Field
This disclosure relates generally to providing enhanced functionality for common radio frequency identification (RFID) technologies and devices, and more specifically to the detection of radio frequency (RF) component alignment, for example, an x-ray critical-alignment apparatus.
2. Description of the Related Art
The general function of a given RFID transponder or “tag” is to act as a “remote sensor device” for a given RF interrogator. When enabled, an RF interrogator's carrier transmit/data receive coil produces an electromagnetic field of flux at a predetermined frequency, which creates a radiated “carrier” transmit signal. When such an RFID tag is placed in close proximity to an RF interrogator, the RFID tag “powers up.” Accordingly, the activated RFID tag is impressed with the carrier transmit signal, and in response certain passive electronic components of the RFID tag begin to self-oscillate, which creates a secondary electromagnetic (EM) field of flux at a predetermined frequency within and about the RFID tag. After the RFID tag is activated and when the received carrier transmit signal is of predetermined ideal amplitude, as set by predefined design criteria of the RFID tag and firmware thereof, the RFID tag begins to transmit a serial data stream of “canned/stored” information. Data transmission is generally accomplished by means of the RFID tag shunting its carrier-receive/data transmit coil or antenna, according to the RFID tag's design and predefined data protocol, etc.
When an RFID tag begins to oscillate so as to radiate a specific RF signal and electromagnetic field of flux, the RF interrogator carrier-transmit coil becomes impressed with the RFID tag's “return” RF signal. The impressed return RF signal upon the RF interrogator carrier-transmit coil is commonly referred to as “backscatter” or a backscatter signal. The backscatter signal generally alters certain characteristics of the RF interrogator carrier-transmit signal. Such carrier-transmit signal alterations, even as they might be minute initially, can be detected by appropriate RF interrogator front-end circuitry. When actual RFID tag serial data stream transmission occurs, the RF interrogator acts to detect the backscatter signal, generally through the use of an “envelope detector” circuit. The RF interrogator will then condition/filter and amplify the backscatter signal to obtain a resultant “clean” data stream signal. Thereafter, the RF interrogator's microcontroller may “test/decode/read” and be configured to respond to the resultant signal, for example, by inputting a product name, code, and price into a cash register when an item containing an RFID tag is scanned, or by setting off an alarm when someone walks out of a store without purchasing an item containing an RFID tag. However, current RFID technology has been limited to its namesake: product “identification.” Thus, the technology has not been applied in alternatively new ways or with regard to differing applications. Accordingly, RFID technology has not been applied to sensor “alignment” functionality, such as for an indication of best alignment of non-contact x-ray film positioning.
During the common and standard process of taking dental x-rays, special tools and several tedious steps are often required. Two options for taking x-rays are known wherein: 1) a molded x-ray film holder, which generally has sharp edges around its periphery, is loaded with an x-ray film and together is placed in a patient's mouth to bite down on (which is most discomforting for most patients due to the sharp edges), such that a dental technician or doctor must then visually estimate the position of the film holder so as to take an x-ray; or, 2) wherein a molded x-ray film holder, also having sharp edges around its periphery, is loaded with an x-ray film and together is placed onto a “rim holder” device (a long bar, generally of metal, with an x-ray film holder receiving device at one end, and an x-ray head apparatus receiving device at the other end), which is then collectively placed in a patient's mouth to bite down on (which is extremely discomforting for most patients due to the sharp edges, as well as due to the bulkiness of the rim holder apparatus) with only the x-ray head apparatus receiving device protruding from the patient's mouth such that a dental technician or dentist would then place the x-ray head into the x-ray receiving device so as to take an x-ray radiograph.
Aside of the general need for special alignment tools, the disadvantages of the above two options are several: 1) often additional x-rays are required to be taken because of improper alignment of the x-ray head apparatus to the x-ray film, especially when the location/position of the x-ray film is manually estimated, and often, when; 2) the rim holder is improperly located/positioned in a given patient's mouth, which creates; 3) loss of both time and expense, and, which additionally; 4) exacerbates a given patient's discomfort. The present disclosure was devised to overcome these challenges. The first concept considered was to provide a system that might permanently eliminate the need for a rim holder device/alignment tool. The second concept considered was to alter the design of the common x-ray film holder device so as to eliminate its sharp edges. The third concept was to identify a system by which the taking of dental x-rays would become less intrusive, yet more accurate.
The basis for RFID technology appears to offer the most ideal solution to the current problems with dental x-rays. Heretofore, RFID technology in practice and application has mostly been used for product and other commodity “identification” purposes. Apparently, such technology had not been used for exacting a critical alignment of an x-ray head apparatus to an (often hidden) x-ray film. One aspect unknown in the art was a system that would permit attachment of a predetermined RF tag in proximity of an apparatus and that would incorporate those components required for building a customary RF tag device. Such a system was lacking in newer technology apparatus (for example, digital radiography) and in well-known technology apparatus, such as dental x-ray film holder devices. Thus, a new RF tag architecture and device is required. However, digital radiography, in terms of equipment and supplies, is extremely expensive, and as it relates to practicing dentists remains of price and expense that is currently highly prohibitive to manifold dentists. Therefore, a great many dentists, especially in rural-type environments, still make use of the established technology such that the dentists are still using both x-ray film and x-ray film holder devices.
Another aspect unknown in the art is an electronics design that would act as an RF interrogator and that would have a remote yet attached “transmit/tag sense/antenna” coil. Such a coil, which transmits a carrier frequency to enable the new RF tag device and that also acts to receive data from the enabled new RF tag device, would need to be devised so as to fit upon or mechanically interface to the active end of a given dental x-ray head apparatus.
One issue in creating a dental-oriented non-contact RF transducer system is that a given dental RF tag must be physically smaller than the accompanying dental RF carrier transmit/data receive coil. In fact, to meet the criteria for obtaining a “best-alignment” scenario with regard to most RF-based transducer alignment systems, a given RF tag thereof, and particularly its RF carrier receive/data transmit coil, must generally remain smaller than the system's associative RF carrier transmit/data receive coil. Another issue to operational practicality for a dental application is that “non-contact” operation be obtained, wherein a given x-ray head apparatus would never (intentionally or need to be caused to) touch a patient's face, especially in the course of alignment of the x-ray head apparatus to the dental RF tag within a patient's mouth. This issue is not in the least trivial since known RFID technology did not allow for spacious RF sensor/tag distance sensing, particularly in wholly scaled-down RFID systems. Various common RF tags currently available were used in test beds, and were found to be grossly lacking as it concerned desired operational distance to a similarly available RF interrogator.
It was found that when an RF tag was placed in a patient's mouth and behind the teeth (as would normally occur in a dentist's office), then valid sensing-distance was no more than one inch, and often much less. The RF interrogators carrier transmit/data receive coil needed to be placed inward on, at or extremely close to the cheek in order to “read” a common RF tag. Thus, commonly available systems were both non-ideal and impractical for a dental x-ray application. Therefore, there is a need for an enhanced RF interrogator analog “front-end” circuit having additional features.
As will be appreciated by those of skill in the art, providing a dental x-ray RFID positioning system incurs several design challenges, including: 1) dental RF tag size, which being rather small, produces only a small RF field of flux at resonance; 2) sensing distance to a given RF tag of at least two inches is desirable; 3) dental RF interrogator carrier transmit/data receive coil size, which also being rather small, has a limited range for detecting a remotely radiated RF signal from an RF tag when an RF tag is activated; 4) data stream signals received by the dental RF interrogator carrier transmit/data receive coil are in the microvolt range when the RF tag is several inches away; 5) such signals, when then fed into operational amplifier circuits, generally can not be distinguished or easily separated from base-noise levels of operational amplifier circuits, and thus, 6) the resultant signal from the operational amplifier circuits contains both inherent and free-air radiated noise, as well as the desired data signals RF carrier transmission components, making “valid” signal detection difficult; and 7) even with filtering, free-air radiated alternating current (A.C.) signals are amplified and become part of the net/final signal structure from the operational amplifier circuits, thereby, grossly affecting the final signal integrity, particularly when obtained by a highly sensitive RF interrogator analog front-end circuit.
Thus, what is needed and heretofore unknown is an RF transducer non-contact alignment system that fulfills dental x-ray application requirements, that solves these identified technical challenges, and that provides a fully operational product. There is also a need for RFID-type technology operable over greater distances between certain types of RF tags and interrogators. There is also a need to fill the technological gaps and voids in the practical applications of RFID technology. There is a further need for critical RF tag/sensor alignment functionality to establish new applications within the RFID industry, especially for critical RF tag alignment.